This invention relates to particle separators and in particular to a particle separator for separating foreign material, such as sand, from a cooling air stream associated with the cooling system of a gas turbine engine.
Gas turbine engines, particularly those used to power aircraft, often must operate in an environment conducive to the entry of foreign particles into the inlet of the engine. In some environments, such as those associated with desert or sea coast areas, sand and other foreign particles from the ground may enter the engine during take-off, landing or hovering operation of the aircraft.
It is well known in the art to provide inlet particle separators disposed at the inlet portion of the engine to separate the foreign particles from the airstream and thereby to protect the components from the abrasive characteristics of the particles. However it has been found that, with the inlet particle separators known in the prior art, not all of the particles, particularly smaller particles such as fine sand, are removed from the airstream. While removal of most of the particles avoids erosion damage to the components of the engine, the presence of the smaller particles presents a problem with the cooling system associated with the engine. More particularly, since some of the air entering the engine inlet is drawn away from the main air stream and utilized to cool the turbine blades of the engine, foreign particles eventually are admitted to the cooling circuit associated with the turbine blades.
Since the cooling passages in the turbine blades are of extremely small diameter, the foreign particles tend to deposit within and clog the circuit passages in the blades. As a result, the amount of cooling air flowing through the passages is reduced and, in some instances, cooling flow is completely restrained if the passages are totally obstructed. Reduced or nonexistant cooling has a detrimental effect upon the life of the turbine blades during engine operation and hence, is a direct cause of high maintenance and replacement costs. This invention addresses the problem associated with clogging of the cooling circuit passages within the turbine blades by sand entrained in the cooling air flow.